Treating corrosive oils



Patented May 25, 1943 TREATING CORROSIVE OILS Charles A. Cohen, Elizabeth,- N. J., assignor to Standard Oil Development Company, a corporation of Delaware No Drawing. Application December 29, 1939, Serial No. 311,592

10 Claims.

This invention relates to an improved process for refining hydrocarbon oils. More particularly, it is concerned with the treatment of oils of the white 011 type such as medicinal oils, transformer oil, insecticide base oils, refrigerator oils, or cosmetic oils and lubricating oils like spindle oil or motor oil which have during the process of their refinement been subjected to the action of fuming sulfuric acid.

Highly acid treated oils or White oils are prepared by the drastic treatment of a hydrocarbon oil having a viscosity in the range of 30-1000 seconds Saybolt at 100 F. with fuming sulfuric acid, followed by separating the acid sludge'from the oil, neutralizing the acid oil with an alkali,

removing the alkali sulfonates from the oil by dilute alcohol or other solvents and steaming the oil to remove the solvent and other volatile constituents. The oil at this stage is known as a neutral oil and varies in color from -10 to Saybolt. It is then finished by percolating it thru a bed of absorbent clay to give a finished white oil of Saybolt in color.

' Many such oils are, however, corrosive in character and will cause the corrosion of copper in less than two hours when subjected to the copper strip test. This test consists in polishing a strip of copper measuring /2 to 3 with tripolii or other fine abrasive, immersing the copper strip in a' sample of the oil to be testedand heating for from 2 to 3 hours in a steam bath at a temperature of 212 F. The results are rated numerically as follows: No. 1 shows no change in appearance of the original copper strip; No. 2 shows a slightly discernable yellow color'but is still passable; No. 3

which fails, shows'a pronounced bronze c'olora-x Some success has been had in treating finished white oils to improve their copper strip test bythe use of calcium .or magnesium hydroxide' However, this method is not applicable to medicinal white oils because oils treated with these reagents acquire an objectionable taste. Also, the quantity of calcium and magnesium hydroxide vsed is bulky and its removal necessitates additional handling of the finished oil which increases the, possibility for contamination.

In addition, there are times when in order to obtain good,

copper strip tests by the calcium and magnesium hydroxide, it has been necessary to give the oil several treatments with these hydroxides.

Alcoholic potassium hydroxide has also been used for the elimination of corrosiveness irom' acid-treated oils and in the proportion of onehalf to 10 lbs. of the dry hydroxide per 1000 gallons of oil afiords some degree of correction when' added to the neutral oil at the end of the steaming period, but this method of treating corrosive oils has several notable objections, the chief among these being the severe degradation in color which takes place and tendency for the finished white oil from the clay percolating'filters to become cloudy after a comparatively short period of time.

It has now been found that acid-treated oils which fail to pass the copper strip test after finishing by percolation thru clay, because of their' corrosive characteristics, may be treated inthe' neutral condition in such amanner that all corrosiveness is prevented and their col-or is much improved.

The present invention is an extension of the process of treating neutral white oils or other acid-refined oils, such as mineral oils or lubr'ieating oils, with alcoholic potassium hydroxide but is devoid of the objectionable features which are in hand in the process of treating these oilswhen only alcoholic potassium hydroxide is used.-

The present invention comprises a process of treating an oil with a solution of an alkali metal hydroxide or alcoholate, for example, alcoholic potassium hydroxide or alcoholic sodium or potassium alcoholate in combination with a hydro of metals which form amphoteric hydrated ox-f alkali sulfonate and heating the oil to from 150 0., preferably C., and adding to the hot oil the alkali compound in an amount equivalent to from to lbs. of dry alkali hydroxide per 1000 gallons of oil, blowing with either hot air freed of carbon oxides, a mixture of hot air and water vapor freed of carbon oxides, or steam, for a time sufficient to; secure intimate contact between the oil and the alkali compound, this is usually from to minutes. The metalloorganic compounds are then added in an amount such that decomposition yields hydrated oxides in the range between .5 and 15 lbs. per 1000 gallons of oil. The oil is then again blown with a finely dispersed stream of hot moist air free of carbon oxides for from 15 to 30 minutes, or for a length of time sufficient to decompose the metallo-organic compounds. For most purposes the passage of air thru the mixture furnishes sufficient agitation to insure an intimate contact be tween the oil and the reagent. However, additional agitation may be secured by mechanical means, such as propeller mixers, centrifugal mixers, such as turbo-mixers or recirculation thru a pump and "the like. The process may be run continuously by concurrent addition of the reagents to the oil in a packed or bubble plate column while countercurrently blowing with moist air or steam. The organic decomposition products of the metallo-organic compounds having been removed during the second air-blowing step in the process, it is advantageous at this point to remove the precipitated oxide in its hydrated form and this can be done by allowing the oil to settle, by centrifuging or by filter-pressing. The filter may be of the blotter, plate and frame or rotary type, and a commercial siliceous filter aid may be used either as a precoat on the filter or mixed with the oil before filtering. After the removal of the hydrated oxides, the oil is found to be much improved in color and for some grades of oils no further treatment designed to improve color is necessary. For highly refined oils, such as medicinal oils which must be colorless, tasteless and odorless, further treatment with a sorptive material, such as fullers earth, bauxite, Attapulgus clay or activated charcoal, may be required. This further improvement of color is accomplished by contacting the oil with the sorptive material in a powdered form or by percolation thru a bed of granular sorptive material of from 30 to mesh. 7

The following example is given for the purpose of illustrating the invention:

Example 1 l000gallons of an acid-treated neutral white oil which had a Saybolt color of -4 and a Universal Saybolt viscosity of 85 seconds at 100 F. was treated at 125 C. with an isopropyl alcohol solution of potassium hydroxide containing 6 lbsqof KOH and blown for 15 min. with a finely dispersed stream of air which had been sodawashed to remove carbon dioxide and then saturated with water at C. At the end of this period 33 lbs. of aluminum isopropylate dissolved in absolutely anhydrous isopropyl alcohol was added and air-blown with hot moist air for a further 30min maintaining the temperature at 125 C. The aluminum isopropylate decomposed to give isopropyl alcohol which was removed with the air and a finely dispersed precipitate of hydrated aluminum oxide. At the end of this period, when all of the alcohol was blown off, the oil was mixed with a small quantity of a diatomaceous filter aid and filtered on a filter press. Upon cooling, the oil had a +13 Saybolt color and gave a pass 1 copper strip test after 2 hours whereas the original oil gave a does not pass 5 test under the same conditions. On percolating the treated oil thru 8% of an adsorbent clay, a water-white oil was obtained of a +30 up color which gave a pass 2 copper test after 2 hours whereas the original untreated oil failed to pass the copper strip test when percolated under the same conditions.

In companion experiments, different samples of the same oil were treated separately; one with KOH and the other with aluminum isopropylate in the same relative proportions as when used in combination so as to give blanks for comparison, unsatisfactory results were obtained. These results are summarized in the table below.

TABLE 1 Treatment of neutral oil with alcoholic potassium hydroxide and aluminum isopropylate Sample A B C 1) Temperature of treat 1 125 125 125 125 Time of air blowing minu tes 30 15 30 45 Mgrn. of KOH per 00.. None 72 None 72 lVIglIl. 01' A1(OC3H7) per 100 cc None N one 400 400 Equiv. mgm. of Al(OH);;

per 100 cc None None 157 157 Saybolt color before percollation..- l. 4 -l3 +10 +13 2 hour copper before percolacion DNP 5 DNP 3 DNP 5 Pass 1 3 hour copper before porcolation DNP 5 DNP 3 BN1? 5 Pass 2 Saybolt color arm porcolation +30 up +27 +30 up +30 up 2 hour copper after porcolation DNP 5 Pass 2 DNP 5 Pass 2 3 hour copper after percolation DNP 5 DNP 3 DNP 5 Pass 2 Sample A is the original untreated oil blank.

Sample B is the original oil treated with only potassium hydroxide.

Sample C is the original oil treated with only aluminum isopropylate.

Sample D is the original oil treated with both potassium hydroxide and aluminum isopropylatc.

It is supposed that the KOH enters into combination with some material, probably related to a sulfonic acid, which has a chromophoric nucleus, but of sufiiciently high enough molecular weight to still remain oil-soluble. When the oil is then treated with a soluble metallo-organic compound which decomposes in situ to give an insoluble, highly adsorbent amphoteric oxide or hydrated oxide, the KOH is adsorbed on the surface of the hydroxide, taking with it the corrosive constituents present and any colored material which it is associated with. It is for this reason that the combination of reagents results in better color improvement than when any of the color reagents are used singly, in spite of the fact that when the KOH is used alone, considerable increase in color results.

The foregoing disclosure and examples are given for the purposes of illustration only and are not to be construed as in any way limiting the invention.

What is claimed is:

1. The process of improving the color and reducing the corrosiveness of acid-treated oils on copper which comprises treating the oil in its neutral state first with strong alkali, then with a compound having the formula Me(X)1,, Where Me is a metal selected from the group consisting of aluminum, tin and zinc; X is a radical selected from the group consisting of alkyl, alkoxy, and alkylhalide radicals, n is a number equal to the valence of the metal radical selected and freeing the oils from the products of reaction.

2. The process of improving the color and reducing the corrosiveness of acid-treated oils on copper which comprises treating the oil in its neutral state first with potassium hydroxide then with a compound having the formula Me(X)n, where Me is a metal selected from the group consisting of aluminum, tin and zinc; X is a radical selected from the group consisting of alkyl, a1- koxy, and alkylhalide radicals, n is a number equal to the valence of the metal radical selected and freeing the oils from the products of reaction.

3. The process of improving the color and reducing the corrosiveness of acid-treated oils on copper which comprises treating the oil in its neutral state with alcoholic potassium hydroxide, blowing with air freed of carbon oxides, adding a compound having the formula Me(X) n, where Me is a metal selected from the group consisting of aluminum, tin, and zinc; X is a radical selected from the group consisting of alkyl, alkoxy, and alkylhalide radicals, and n is a number equal to the Valence of the metal radical selected, blowing the oil with warm moist air freed of carbon oxides and freeing the oil from the products of reaction.

4. The process of improving the color and reducing the corrosiveness of acid-treated oils on copper which comprises treating the oil in its neutral state with potassium alcoholate, blowing with air freed of carbon oxides, adding a compound having the formula Me(X)", where Me is a metal selected from the group consisting of aluminum, tin, and zinc; X is a radical selected from the group consisting of alkyl, alkoxy, and alkylhalide radicals, and n is a number equal to the valence of the metal radical selected, blowing with warm moist air freed of carbon oxides and freeing the oil from the products of reaction.

5. The process of improving the color and reducing the corrosiveness of acid-treated oils on copper which comprises treating the oil in its neutral state first with strong alkali, then with an organic compound of aluminum, the organic radical of which is selected from the group consisting of alkyl, alkoxy and alkylhalide radicals, blowing with warm moist air freed of carbon oxides and freeing the oil from the products of reaction.

6. The, process of improving the color and reducing the corrosiveness of acid-treated oils on copper which comprises treating the oil in its neutral state first with strong alkali, then with aluminum alcoholate, blowing with warm moist air freed of carbon oxides and freeing the oil from the products of reaction.

'7. The process of improving the color and reducing the corrosiveness of acid-treated oils on copper which comprises treating the oil in its neutral state first with strong alkali, then with tin alcoholate, blowing with warm moist air freed of carbon oxides and freeing the oil from the products of reaction.

8. The process of improving the color and reducing the corrosiveness of acid-treated oils on copper which comprises treating the oil in its neutral state first with strong alkali, then with zinc alcoholate, blowing with warm moist air freed of carbon oxides and freeing the oil from the products of reaction.

9. The process of improving the color and reducing the corrosiveness of acid-treated white oils which comprises heating the oil to from -150 C., adding alcoholic potassium hydroxide in an amount equivalent to from .5 to 10 lbs. of KOH per 1,000 gallons of oil, blowing with air freed of carbon oxides, adding a compound having the formula Me(X), where Me is a metal selected from the group consisting of aluminum, tin, and zinc; X is a radical selected from the group consisting of alkyl, alkoxy, and alkylhalide radicals and 11. is a number equal to the valence of the metal radical selected in an amount equivalent to 1.5-15 lbs. of amphoteric hydrated oxide per 1000 gallons of oil, blowing with hot moist air freed of carbon oxide and filtering and percolating the filtered oil through a sorptive material.

10. The process of improving the color and reducing the corrosiveness of mineral white oil on copper which comprises heating the oil to 0., adding alcoholic potassium hydroxide in an amount equivalent to between .5-10 lbs. of potassium hydroxide per 1000 gallons of oil, thoroughly agitating the mixture, adding aluminum isopropylate in an amount equivalent to between 15-15 lbs. of hydrated aluminum oxide per 1000 gallons of oil, blowing with warm moist air until all of the aluminum alcoholate has been decomposed, filtering and percolating the oil through a bed of sorptive material.

CHARLES A. COHEN. 

